Answer: Option B. is the right answer.The length of QT is 65 cm.
Explanation:
Given:In ΔRST ,PQ is a line parallel to RS and dividing RT and ST in same ratio(by Basic proportionality theorem)

Basic Proportionality theorem states that if a line is drawn parallel to one side of a triangle to intersect the other two side in distinct points, the other two sides are divided in the same ratio.
Therefore, the length of QT is 65 cm.